Method of making electrolytic condensers and preparing electrodes therefor



Patented May 16, 1933 UNITED STATES PATENT OFFICE smear. RUBEN, or NEW ROCHELLE, new You. Assiea'oa 'ro RUBEN oommusna COMPANY, OF NEW ROCHELLE, NEW YORK. A COBP QBATION OF DELAWARE METHOD OF MAKING ELECTROLYTIC CONDENSEBS AND PREPARING ELECTRODES THEREFOR No Drawing.

This invention relates to a method of making electrolytic condensers of the type com nionly known as dry electrolytic condensers and in preparing the anode member prior toassembly.

A general object of the invention is the provision of such a method which insures the economical, eflicient and uniform productlon of condensers of this type having a low power factor and series resistance, and a degree of mechanical perfection heretofore unattainable uniformly in commercial production.

A more specific object of the invention 1s the provision of such a method whereby the film-formed anode member is provided with a coating of viscous bonding liquid which insures uniform contact between the film-face of the anode member and the film-maintaining composition or electrolyte, and a low power factor and series resistance. 7

A further object of the invention is the provision of such a method whereby the filmformed anode member prior to assembly in the condenser is cleaned and then coated with a viscous bonding liquid miscible with the film-maintaining composition and including or consisting of one or more of the polyhydric alcohols or products thereof having two or more hydroxyl radicals which insures efiicient electrical contact between the film-maintaining composition and substantially the entire area of the anode member adjacent thereto, uniformity in production and operating characteristicsand a very low power factor and series resistance.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others thereof, which will be exemplified in the method hereinafter disclosed, and the scope of the application of which will be indicated in the claims. 1

Prior to the present invention electrolytic condensers of two types have been used, the gaslayer polarized cell type and the electrolytically formed film layer type. The electrolytic condensers made by the method of Application fled. mu 1:,

.in relatively high heatlosses and a ism. mm 10. 004,010.

as, for example, aluminum, tantalum, magnesium or alloys thereof, provided with an electrolytically formed current-blocking film. Between these electrodes is disposed a body or layer of a viscous composition of paste consistency which may be spread on suitable spacer material used as a separator for the electrodes. In its usual form this composition comprises a vehicle in which is suspended a suitable film-forming electrolyte. This vehicle is usually a polyhydric alcohol having two or more hydroxyl radicals, for example, a glycol or a glycerol.

When such condensers are used in power filter circuits where efiiciency and high capacitances are essential, those known to the prior art have been found to have certain undesirable limitations. The resistance of the electrolyte or film-maintaining composition being relatively high gives a relatively high series resistance to such condensers, resulting high power factor. Furthermore, in commercial production it has been found that the effective area of the film-formed anode member is considerably reduced by separation between the film-maintaining composition or electrolyte and the anode member. This is more frequently experienced in the coil type wherein the electrodes are wound up with spacer material spread with film-maintaining composition interposed between the electrodes. In the so-called dry electrolytic condensers wherein the film-maintaining composition or electrolyte is of paste consistency there is usually found a somewhat granular structure which has a relatively low surface flexibility. Areas of separation thus appear when thin layers thereof are deformed. In addition these difiiculties make unllformity in commercial production difiion t.

By the present invention an economical method of making such electrolytic condensers and preparing the anode member 1 thereof is provided, which substantially eliminates these difliculties of the prior art and which is particularly adapted for the improvement of electrolytic condensers comprising aluminum electrodes, one of which is provided with a current-blockin g film preferably separated by spacer material upon which is spread a com osition including a glycol or glycerol, pre erably ethylene glycol, and a film-maintaining electrolyte, preferably ammonium borate and boric acid.

The method of the present invention comprises coating the film-formed electrode with a viscous bonding liquid miscible with the film-maintaining composition prior to assembly in the condenser unit. Any practicable method of applying such a coating to a film-formed electrode may be used in accordance with the present invention. The

referred method, however, is as follows: The metal electrode, preferably in the form of a sheet, is electrolytically treated in a suitable electrolyte so as to have formed on it a current-blocking film, and is then cleaned, preferably by passing the film-formed sheet successively through a bath of alcohol and a bath of water, distilled water being preferred to prevent undue contamination. The cleaned film-formed sheet is then preferably passed through or dipped into the chosen viscous bonding liquid to provide a thin coating thereof on the film-formed electrode sheet. Spacer material is then placed on the sheet and spread with a layer of suitable film-maintaining composition preferably viscous and of plastic consistency and of a less degree of fluidity than the vlscous bondin liquid, so that the coating of bonding liqui makes intimate contact with the film-maintaining com osition. A second electrode plate, the cat ode, is then laid over the spacer material and film-maintaining composition, the latter bein compresed between the two electrodesto insure good physical contact between 'the anode, the viscous bondin liquid, the film-maintaining composition an the cathode. If the condenser is to be rolled, another layer of s acer material is then placed over the cat ode, spread with filmmaintaining composition, and the rolling carried out in the usual manner.

The viscous bonding li uid ma consist of or include one or more of t e poly ydric alcohols or products thereof having two or more h droxyl radicals, such as, for example,

'g ycerine, ethylene glycol, glucoses, etc. The

condensers; the term film-formed electrode is used to designate an electrode of suitable valve metal provided with a current-blocking film; and the term film-maintaining com sition is used to designate-an composition used in the final assembl inc uding a filmmaintaining electrolyte or the purpose of maintaining a current-blocking him on the electrode.

While I do not wish to limit myself to any particular theory mg of viscous onding liquid on the filmformed electrode serves as a protection for the current-blocking film thereon and in addition provides a flexible electrical bond between the film-maintaining composition and the current-blocking film of the electrode insuring electrical contact therebetween substantially throughout the entire area of the film-formed electrode over which the filmmaintainin composition lies. It serves to bring the e ectrical charge from the cathode through the film-maintaining composition to the current-blocking film on the anode and thus provides maximum capacitance per unit of electrode area and reduces the series re sistance and the power factor of the condenser unit to a minimum. For example, tests have shown that prior to the present invention condensers comprising aluminum electrodes and a film-mamtaimng composition of ammonium borate, boric acid and ethylene glycol having a capacity of 10 mfd. under the best conditions have a resistance of about 3 to 4 ohms. Similar condensers made in accordance with the method of the present invention, that is, by providing the anodes with a coating of viscous bonding liquid prior to the a plication of the spacer ma-. terial and fi m-maintaining composition, have been found to have a resistance of around 1 ohm. The avera power factor of the latter units has been ound to be better it is believed that the coat-- than one per cent as compared with a power factor of about 3 to 4 per cent for the former units and a surprising uniformity in these units has been attained in commercial production.

It will thus be seen that in accordance with the present invention a method for making electrolytic condensers and prepa electrodes therefor has been provided which eficiently attains the objects set forth above. The characteristics of electrolytic condensers made in accordance with the present invention indicate an efficiency operation and possible fields of use, such as, for example, in alternating current work and more particularly in motor starting, due to the extremely small resistance loss, heretofore unattainable with the best condensers of this type available prior to the present invention.

Since certain changes me be made in carryin out the above meth without departing rom the scope of the invention, it 18 intended that all matter contained in the above description shall be interpreted as illustrative and not in a limitin sense.

It is also to be un erstood that the following claims are intended to cover all of the neric and s ific features of the invention erein descri and all statements of the scope of the invention which as a matter of Ian uage, might be said to fail therebetween. aving described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. The method of preparing electrodes for electrolytic condensers of the so-called' dry type having a film-maintaining composition of at least paste consistency comprising applying a coating of viscous bonding liquid to electrode metal provided with a currentblocking film, said coating being adapted to form a bond between the current-blocking film and the paste-like film-maintaining composition when the elements of the condenser are assembled.

2, The method of preparing electrodes for electrolytic condensers of the so-called dry type having a film-maintaining composition of at least paste consistency comprising cleaning film-formed electrode metal and aplying thereto a coating of viscous bonding iquid, said coating being adapted to form a bond between said film-formed electrode and the paste-like film-maintaining composition when the elements of the condenser are assembled.

3. The method of preparing electrodes for electrolytic condensers of the so-called dry type having a film-maintaining composition of at least paste consistency comprising applying a coating of viscous bonding liquid including one or more of the polyhydric alcohols or products thereof having two or more hydroxyl radicals to electrode metal provided with a current-blocking film, said coating being adapted to form a bond between the current-blocking film and the paste-like film-maintaining composition when the elements of the condenser are assembled.

4. The method of preparing electrodes for electrolytic condensers of the so-called dry type having a film-maintaining composition of at least paste consistency comprising ap plying a coating of viscous bonding liquid including a polyhydric alcohol falling within the classes glycols and glycerols to an aluminum member provided with a currentblocking film, said coating being adapted to form a bond between the current-blocking film and the paste-like film-maintaining composition when the elements of the condenser are assembled.

5. The method of preparing electrodes for electrolytic condensers of the so-called dry type havinga film-maintaining composition of at least paste consistency comprising cleaning a film-formed aluminum member and applying thereto a coatin of viscous bondin liquid including a poly dric alcohol fal ing within the classes g ycols and glycerols, said coating being adapted to form a 0nd between said film-formed electrode and the paste-like film-maintaining composition when the elements of the condenser are assembled.

6. The method of preparing electrodes for electrolytic condensers of the so-called dry type having a film-maintaining composition of at least aste consistency comprising passing a filmormed aluminum member through a bath of ethylene glycol, to provide thereon a coating adapted to form a bond between said film-formed electrode and the paste-like film-maintaining composition when the elements of the condenser are assembled.

7. The method of preparing electrodes for electrolytic condensers of the so-called dry type having a film-maintaining composition of at least paste consistency comprising passing a film-formed aluminum member successively through baths of alcohol, water and ethylene glycol, to clean said film-formed composition with which it is miscible to electrode metal provided with a current-blocking film, said coating being adapted to form a bond between the current-blocking film and the paste-like film-maintaining composition when the elements of the condenser are assembled.

9. The method of making electrolytic condensers which consists in cleaning a filmformed anode, applying a coating of viscous bonding liquid to said anode, applying a filmforming composition of paste consistency thereto and bringing a second electrode member into physical contact with said composition. I

10. The method of making electrolytic condensers which consists in providing an aluminum sheet anode member with a current-blocking film, cleaning said film-formed anode member, coating said anode member with a viscous bonding liquid including one or more of the polyhydric alcohols or products thereof having two or more hydroxyl radicals applying to the said coated anode a film-forming composition of paste consistency and bringing a second electrode member into physical contact with said composition.

11. The method of making electrolytic condensers which consists in providing an aluminum sheet anode with'a current-blocking film, pass said film-formed anode member successive y throu h baths of alcohol, water, and a viscous bon ing'liquid including one or 5 more of the polyhydric alcohols or products thereof having two or more hydroxyl radicals applying to said anode member a filmforming composition of paste consistency, and bringing a second electrode member into 10 ph sical contact with said composition.

2. The method of making electrolytic condensers which consists in providing an aluminum sheet anode member with a currentblocking film, passing said film-formed anode member successively through. baths of alcohol, water and ethylene g1 col and positioning said anode member a iacent to another electrode member spaced therefrom by spacer material and a film-forming composition of paste consistency including ammonium borate, boric acid and ethylene glycol.

13. The method of making electrol ic condensers which consists in passing s set aluminum successively through a film-forming electrolyte, a bath of alcohol, a bath of water and ethylene glycol and winding up into coil form said treated aluminum sheet with another sheet of metal having a strip of spacer material on each face thereof provid- 39 ed with a composition of paste consistency including ammonium borate, boric acid and ethylene glycol.

In testimony whereof I afiix m si ature.

SAMUEL U EN. 

